Can't get exception's message in Django custom validator

Question

I'm writing a custom validator that receives a list of validators, and checks if any of them passes, so you can easily check for things like this integer field should be lower than 10 or higher than 100. This is what I have so far:

class ValidateAnyOf(object):
    def __init__(self, *validators):
        self.validators = validators

    def __call__(self, value):
        errors = []
        for validator in self.validators:
            try:
                validator(value)
                return
            except ValidationError as e:
                errors.append(e.message)

        raise ValidationError('Combined validation failed:' + ','.join(errors))

class TestModel(models.Model):
    score = models.IntegerField(validators=[ValidateAnyOf(validators.MaxValueValidator(10),
                                                          validators.MinValueValidator(100))])

The logic is ok. The problem arises when none of the validators passes. I want to show a list of the errors, so I store in a list the messages from the exceptions. The problem is that e.message seems to be a django.utils.functional.__proxy__ object, instead of a string, so I can't join them to show the full error message.

How can I get the error message from each exception?

sk1p · Accepted Answer · 2013-12-14 05:33:30Z

1

They are an instance of django.utils.functional.__proxy__ because the message of the Django core validators is translatable and wrapped in ugettext_lazy. I think you can use something like ", ".join(unicode(e) for e in errors) to force evaluation of the message.

answered Dec 14, 2013 at 5:33

sk1p

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2 Comments

José Tomás Tocino Over a year ago

unicode(e.message) did the trick. I had to manually pass the params for the placeholders using errors.append(unicode(e.message) % e.params) and it worked.

ybendana Over a year ago

You can also now use django.utils.encoding.force_text instead of unicode.

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